Strontium-90 has a half-life of 28 days. Find the mass (in mg) remaining after 20 days. (Round your answer to one decimal place.) mg

Ascale drawing of a lake has a scale of 1 cm to 80 m. if the actual width of the lake is 1000 m what is the width of the lake on the scale drawing

Use this data in the problem below. follow the steps carefully. round to the nearest tenth. lot 3: week 1: 345 week 2: 340 week 3: 400 week 4: 325 step 1. jim enters the data and calculates the average or mean. step 2. jim calculates the deviation from the mean by subtracting the mean from each value. step 3. jim squares each deviation to remove negative signs. step 4. jim sums the squares of each deviation and divides by the count for the variance. step 5. jim takes the square root of the variance to find the standard deviation.

1. there are 25 students who started computer programming in elementary school and 25 students who started computer programming in middle school. the first group had a mean final project grade of 95% and the second group had a mean final project grade of 92%. the line plot shows the differences after 10 rerandomizations. determine whether the difference in the means of the two groups is significant based on the line plot. explain your answer.